This invention relates generally to electric motor devices such as power tools, and more particularly to an insulating motor housing having a motor shaft support and heat sink secured therein. The invention includes the method of accurately and inexpensively assembling the heat sink to the housing and forming or locating a motor shaft bearing in the heat sink.
Portable electric devices such as power tools, often include electrically insulating motor housings for good electrical insulation. Of these, a number employ thermoplastic materials because of the versatility, impact resistance, and attractive appearance of those materials. These electrically insulating materials, however, are also poor heat conductors, and care must be taken to ensure good heat dissipation. Otherwise, heat build up during use of the device can shorten the life of the moving parts. Also, excessive heat accumulation can soften and possibly distort the thermoplastic housing material, and this is a particularly undesirable condition especially where the thermoplastic material is a structural part of the device, e.g., a structural support for one of the motor shaft bearings.